<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
	<style type="text/css">
		 .box{
		 	width: 0px;
		 	height: 0px;
		 	border: 100px dotted;
            /* transparent 透明 */
		 	border-color:  red green yellow blue;
		 }
	</style>
</head>
<body>
 <div class="box"></div>
</body>
</html>